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Control segment-based lever-arm correction via curve fitting for high accuracy navigation

a technology of curve fitting and control segment, applied in the field of space-based navigational systems, can solve the problems of affecting the ability of gps receivers to determine their position, displaced phase center of each antenna, and rms of vertical navigation error, and uncompensated ure can produce up to nine meters (rms) of vertical navigation error

Inactive Publication Date: 2007-05-22
THE BOEING CO
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

One difficulty with this approach is that the high gain spot beam antenna is typically physically displaced from the wide beam antenna, and consequently, the phase center of each antenna is also displaced as well.
This displacement is known as the “lever arm” between the antennas, and left uncorrected, can negatively affect the ability of the GPS receivers to determine their position.
Depending on the GPS satellite constellation, this uncompensated URE can produce up to nine meters (RMS) of vertical (altitude) navigation error, which is a factor of 10 higher than the performance of the current GPS constellation of 0.9 meters (RMS).
In civil aviation applications, such errors are sufficient to result in loss of life, and in military applications, they can result in increased collateral damage, and increased sortie and weapon consumption to perform the same mission.
Further exacerbating this problem is the fact that in order to maintain proper Sun and Earth pointing, the GPS satellites are required to perform attitude maneuvers.
Such maneuvers can be very large, particularly about yaw axis.

Method used

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  • Control segment-based lever-arm correction via curve fitting for high accuracy navigation
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  • Control segment-based lever-arm correction via curve fitting for high accuracy navigation

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Embodiment Construction

[0026]In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments of the present invention. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0027]FIG. 1A illustrates a three-axis stabilized satellite or spacecraft 100. The satellite 100 has a main body 102 (which may be referred to as the “satellite bus”), one or more solar panels 104, one or more navigation beam antennas 106E and 106S, and a telemetry and command antenna 108 which is used to communicate with a control ground station. The satellite 100 may also include one or more sensors 110 to measure the attitude of the satellite 100. These sensors may include sun sensors, earth sensors, and star sensors. Since the solar panels are often referred to by the designations “North” and “South”, the solar panels in FIG. 1A are refe...

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Abstract

A method and apparatus for estimating a lever arm correction between the wide beam antenna and the spot beam antenna in a navigational satellite system is disclosed. A prescribed satellite maneuver is used to increase the accuracy of the predicted satellite attitude in determining the lever arm, and lever arm corrections are provided from a ground segment to navigation receivers using curve fit coefficients to permit long range estimates and to minimize data transmission requirements.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Application Ser. No. 11 / 247,641, entitled “SPACE-BASED LEVER ARM CORRECTION IN NAVIGATIONAL SYSTEMS EMPLOYING SPOT BEAMS,” by Jonathan A. Tekawy and Kevin M. O'Brien, and filed on same date herewith; and[0002]Application Ser. No. 11 / 247,493, entitled “USER SEGMENT-BASED LEVER ARM CORRECTION VIA PRESCRIBED MANEUVER FOR HIGH-ACCURACY NAVIGATION,” by Jonathan A. Tekawy and Kevin M. O'Brien and filed on same date herewith.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]The present invention relates generally to space-based navigational systems, and in particular, to a control segment-based lever arm correction system applicable to navigational systems employing spot beams.[0005]2. Description of the Related Art[0006]The Global Positioning System (GPS) is a satellite system that transmits navigation signals that are received by ground-based GPS receivers and used to determine the position of the GPS receiver to a high degree of...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H04B7/185G01S19/02
CPCB64G1/1014B64G1/24B64G1/244
Inventor O'BRIEN, KEVIN M.TEKAWY, JONATHAN A.
Owner THE BOEING CO